Although the history of fluorescent whitening agents in China is not very long, they have been widely developed in their current use. No matter what industry needs to use fluorescent whitening agents, fluorescent whitening agents can be divided into yellow light and blue light. Next, I will teach you the methods of using fluorescent whitening agents.
There are generally two uses of blue fluorescent whitening agents in plastics: dry method and wet method.
Dry whitening refers to adding a certain amount of whitening agent dry powder directly to the formed plastic base particles. It is first thoroughly mixed with the plastic base particles, and when the extruder reaches the plastic melting temperature, the mixture is squeezed into the screw to melt, so that the fluorescent whitening agent is evenly dispersed in the melt, and then granulation is carried out. This dry whitening method is mainly used for injection molding whitening of thermoplastic resins such as hard polyvinyl chloride, polyethylene, and polypropylene, and the operation is relatively convenient. The disadvantage is dust dispersion pollution.
The wet whitening of blue fluorescent whitening agents is to add the whitening agent to the additives used in plastic processing, and add them in batches in the form of additive dispersions. For example, in the processing of soft PVC, fluorescent whitening agents can be mixed into a 10% solution of dioctyl phthalate plasticizer and added in batches. The advantage of this wet whitening method is that it reduces dust pollution, but the disadvantage is that it often increases the viscosity of the formed product, so it is only suitable for whitening soft PVC.
